1/ Sources: Country data sources is from the "World Road Statistics-2011," International Road Federation, including the United States which supplies the data to the International Road Federation, from FHWA's annual Highway Statistics report.

2/ Data includes mainland China and China Hong Kong.

3/ Data is from the U.S. Department of Transportation, Federal Highway Administration, Highway Statistics series, Table HM-20M. Major roads include: Interstate, Other Principal Arterials, Other Freeways and Expressways, and Major Collectors. Secondary roads include Minor Arterials, Minor Collectors, and Local roads . Does not include Puerto Rico. Data is for 2009.